Jim,Agreed, I realize that my "kind of" wasn't clear on that point, glad you clarified. I agree tinkering w/ P can cause all kinds of headaches that a relay or just flipping the steam switch can avoid. Have you ever tried any of these methods with Silvia? Specifically ramp/soak or relay?

I'm just curious as to whether this is simply the "PID" tickling the boiler during the shot, or whether the group is being slowly heated by the brew water, and is therefore having a progressively-diminishing cooling effect on the brew water passing through it during the shot ? Is this after pulling a "warming" flush before the shot ?

It seems to me that there's a balance point between the steadily-rising shot temperature potentially due to group heating, and the actual water temperature in the boiler at the end of the shot. If you apply much heat to the boiler whilst pulling the shot, you will minimise recovery time at the expense of poor shot stability because of this.

Perhaps that's an obvious assessment of the situation, but I'd not actually thought about it like that before.

Jim,Agreed, I realize that my "kind of" wasn't clear on that point, glad you clarified. I agree tinkering w/ P can cause all kinds of headaches that a relay or just flipping the steam switch can avoid. Have you ever tried any of these methods with Silvia? Specifically ramp/soak or relay?

Never tried either of those ideas (except I once experimented with a 30 minute ramp for cold startups - not good). I'd have to give some more thought to the possible benefits of these, though. The idea of forcing the heating element on as early as possible during a shot sounds like the right thing, but also seems contradictory to what I have observed with the shot temperature rising at the end.

In any event, I think intrashot temperature is already a Silvia strong point. Controlling the intershot temperatures is, IMHO, the bigger challenge.

Posted Fri May 4, 2007, 7:53am Subject: Re: Going for the PID kit for Sylvia from Jim Gallt...Please confirm this is wis

JonS Said:

Jim, do you have a comparison with a non-PID silvia on this ?

I'm just curious as to whether this is simply the "PID" tickling the boiler during the shot, or whether the group is being slowly heated by the brew water, and is therefore having a progressively-diminishing cooling effect on the brew water passing through it during the shot ? Is this after pulling a "warming" flush before the shot ?

It seems to me that there's a balance point between the steadily-rising shot temperature potentially due to group heating, and the actual water temperature in the boiler at the end of the shot. If you apply much heat to the boiler whilst pulling the shot, you will minimise recovery time at the expense of poor shot stability because of this.

Have never compared the temp profiles with a non-PID Silvia (does anybody actually have one of these? :-) )

The lag time between application of power and observable boiler temp change is in the 25 second range on the Silvia. So, my speculation is that the heater would be best able to affect the later stages of the shot. When I am being careful, I try and pull shots when the group temperature is stable, either after a long idle period, or after the effects of any flushes have dampened out. So a flush would probably not have much effect for my protocol.

Oddly, I find that the PID is better able to handle recovery when the boiler temperature drop is large, i.e., when the temperature has dipped down as much as possible. Shots that are slow, or long duration shots, can give the PID some control challenges as it directs the recovery.

In these cases, the heater element ends up with a bunch of heat stored that the PID doesn't "know" about. The result frequently is higher overshoot, and slower recovery from a small temperature drop than from a large one. So recovery time might actually be lengthened, in some cases, by "manually" applying heat during the shot.

Every PID algorithm seems to behave a little differently. On your Cal controller, I have found that the shortest path to recovery is through allowing a large overshoot. The Cal algorithm seems to be smart enough to know it has overshot the mark and allows things to cool off quickly. IIRC, the most effective overall tuning on the Cal's pretty closely followed what ZN tuning gives you.

Doing it yourself is cheaper and you will be satisfied even with less than the best parts. If money is no object, Jim's piece should be perfect, it's a quality piece and he takes pride in it. I however, prefer RTD's over Thermo's. Next step for you is to add a timer and pressure gauge. www.flickr.com/photos/inkstar

I figured I may as well see how far I could go with it. Since I was roasting my own beans, and extracting with as Naked a portafilter as that design allowed, I may as well dabble with a PID at an affordable price point, when dipping my toe in.

No going back. A wonderful improvement to ease of use, and shot quality.

That said. Why RTD? I tried one (note the decimal place in the display). But I found the response time too slow. I could program around it but the warm up seemed glacial then, and very much prone to overshoot.

As soon as I switched to a TC, things were much easier.So the obvious flaw with the Barista is the tiny boiler, and the temperature drop once you start pulling a shot (the silver lining being how quickly you can pull your first shot after the very quick warm up). With the RTD I'd be done my shot before the PID started trying to catch up. With the TC, it noticed immediately and starting calling for constant heat through the shot, minimizing the temperature loss, in fact I often gain much of it back by the time the shot is done. At this point the RTD would also be slow sensing that it had long overshot the set point, whereas with the TC, by the time the shot is done, it only has to make up 5-10 degrees, and at most goes over by 1-2 deg before settling in.

I was most pleased with how easily the PID integrated into the Barista though. Plug and play. It could be Factory/Stock configured again in 5 minutes. (The PID is held onto the side magnetically).

PID is a good idea. The temperature swing in Silvia's boiler because of the button thermostat is ridiculously wide (as it is with virtually all home espresso machines with a single boiler).

Jim's kits are excellent. Sure, you can assemble the major parts on your own for a lot less, but his wiring is all pre-cut with terminals installed. Jim has spent a lot of time putting together his step-by-step instructions which make it an easy matter to install if you are comfortable with basic hand tools.

Read the review I have posted on my website for more details: http://www/EspressoMyEspresso.com

Doing it yourself is cheaper and you will be satisfied even with less than the best parts. If money is no object, Jim's piece should be perfect, it's a quality piece and he takes pride in it. I however, prefer RTD's over Thermo's. Next step for you is to add a timer and pressure gauge. www.flickr.com/photos/inkstar

I saw your photos - awesome! Where did you get your timer & how did you wire it in to the Silvia ciruit? Does it start when you rock the brew switch, or do you have to start it separately? I am looking ofr a 2-digit countdown timer with audible alarm. I would like to have it start when I hit the brew switch, & then beep when at 25 seconds (at zero on the countdown) so that I would know the shot should be done or close to it.

I can't seem to find one on the web, & don't know enough about electronics to get the chips, etc.. to make one myself.

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